1. Field of the Invention
This invention relates to novel compositions capable of readily forming aqueous gel.
2. Description of the Prior Art
The aqueous gel is widely used as extinguishant, soil stabilizers, thickeners, adhesion modifiers, dyeing auxiliaries or the like. There are two classes of the aqueous gel, one with a very high viscosity still a fluidity and the other being solid or semi-solid without fluidity. In a broad sense, both are called aqueous gels. Illustrative of the former are aqueous solutions of a water-soluble macromolecular substance such as sodium alginate, carboxymethylcellulose sodium salt and polyacrylic acid sodium salt. These are utilized as a glueing agent, thickener or the like. In order to obtain an aqueous gel of high viscosity, however, concentration of the macromolecular substance dissolved should be high. As their solutions are high in viscosity upon preparation, they are not suitable for uses where a viscosity as low as possible prior to use is preferable. There has been found processes with sodium polyacrylate in which the solution is low in viscosity prior to use but yields an aqueous gel when used by, for example, mixing an aqueous solution of polyacrylic acid with an aqueous solution of an alkali such as sodium hydroxide just prior to use. The process, however, causes another trouble in that the aqueous solution is alkaline. On the other hand, an example of the latter is an aqueous solution of polyvinyl alcohol and boric acid. As the active components are two in this case, aqueous solutions respectively containing the two component can be mixed just prior to use to prepare an aqueous gel. It is possible by the process to eliminate the aforementioned problems if needed. However, the polyvinyl alcohol-boric acid system has not yet found wide use, because mixing of aqueous solutions at relatively high concentrations is required in order to produce an effective aqueous gel.